The American population is treated for nearly eight million long bone fractures per year. Approximately 10% of these fractures do not heal properly. Many of these non-unions or pseudoarthroses result when there is a severe or communited (highly fragmented) condition that does not proceed through a stabilized (intramembranous ossification) healing pathway. Early detection of aberrant healing would allow for newer classes of more non-invasive revision strategies to be utilized, as well as ease the technical demands of more open revision procedures. Unfortunately, the course of aberrant fracture healing is not easily diagnosed in the early time period when standard radiographic information of the fracture site is not capable of discriminating the healing pathway. We have hypothesized that healing in the critically important early time period can be determined by monitoring of the implanted hardware mechanics. This postulation leverages the previously demonstrated phenomena whereby the soft tissue callus and newly formed bone progressively assume part of the load as healing proceeds, thus reducing the burden (and associated strain) on the implanted hardware. Thus, to address the critical need of identifying aberrant fracture healing during the early time period, we have developed a wireless, inductively-powered (no implantable power source), biocompatible micro-electromechanical sensor (bioMEMS) that is capable of monitoring the surface strain on implanted bone fracture hardware and reports these data using radio frequency (RF) technology. This development proposal seeks funding to further these activities and to establish the sensor's ability to discern normal versus aberrant bone healing using in vitro and animal models. In order to achieve these goals, we propose three specific aims: 1 - to optimize the sensor's architecture for detecting strain, 2 - to fully characterize the sensor's response in a simulated fracture and physiological environments, and 3 - to implement the sensor in an animal model of normal and aberrant fracture healing to test our guiding hypothesis and perform rigorous biocompatibility analyses. In summary, this developmental proposal seeks to evolve our bioMEMs sensor from the benchtop to the in vivo environment. The research plan represents a logical progression of experiments that are required to demonstrate the safety and efficacy of the device. It is expected that at the end of this project that sufficient data will have been obtained in order to file an application for clinical trial in human patients. PUBLIC HEALTH RELEVANCE: The American population is treated for nearly eight million long bone fractures per year and approximately 10% of these fractures do not heal properly. Unfortunately, the course of aberrant fracture healing is not easily diagnosed in the early time period when more non- invasive revision strategies could be employed. Thus, to address the critical need of identifying aberrant fracture healing during the early time period, we have developed a wireless, inductively-powered (no implantable power source) and biocompatible sensor that is capable of detecting the course of bone healing and reports these data using wireless technology.